1. Field of the Invention
The invention relates to catheters which are adapted to be inserted in ducts and passages within the body as well as blood vessels including arteries and veins for the removal of blockages, obstructions, occlusions, or the like therefrom. More in particular, the invention relates to laser angioplasty, the use of laser energy to disintegrate or to vaporize plaque in coronary, femoral and other arteries. Laser angioplasty comprises the directing of a catheter which is adapted to transmit laser energy, into a blood vessel and the advancing of the free end of the catheter within the blood vessel to the location of an occlusion or arteriosclerotic plaque within the blood vessel. The catheter delivers laser energy to the location to disintegrate or vaporize the occlusion, thereby opening an obstructed blood vessel.
The use of the intense and concentrated energy of a laser within a portion of the body such as a blood vessel presents the possibility of perforation of the blood vessel and damage to the surrounding tissue. Accordingly, a catheter using laser energy must confine such energy to the obstruction to be removed.
2. Description of the Prior Art
Conventional catheters for laser angioplasty have a flexible outer tube which can be inserted into a blood vessel. Within the outer tube is disposed a bundle of optical fibers which extend to adjacent the distal end of the outer tube. A laser is connected to the bundle for transmitting laser energy to an occlusion within the blood vessel. Debris resulting from the vaporizing of the occlusion by the laser can be removed by applying suction to the outer tube.
U.S. Pat. No. 4,207,874 which issued to Choy on Jun. 17, 1980 for a "Laser Tunneling Device" is an example of a catheter having a bundle of optical fibers. The catheter is adapted to be advanced within a blood vessel to adjacent an occlusion or calcified plaque for the application thereto of the energy of a laser. Suction can be applied to the laser to remove the debris resulting from the vaporization of the occlusion.
U.S. Pat. No. 4,224,929 which issued on Sep. 30, 1980 to Furihata for "Endoscope with Expansible Cuff Member and Operation Suction" discloses an endoscope adapted to be placed in a blood vessel. A pair of cuff members spaced apart from one another and disposed adjacent the distal end of the endoscope is adapted to be expanded to contact the inner walls of the blood vessel and to form a chamber between the cuff members. A procedure such as observation, surgical treatment, etc. can then be performed within the chamber formed by the cuff members and the blood vessel.
U.S. Pat. No. 4,240,431 which issued on Dec. 23, 1980 to Komiya for "Laser Knife" discloses a device using laser energy for the incision or excision of an affected part of the body. In order to prevent the laser energy from causing undesirable cautery or piercing of normal tissue adjacent that which is to be treated, the laser energy is intercepted by a receiving surface, once the cutting procedure is completed.
Russian Patent No. 938,977 which issued on Mar. 12, 1980 to Zaitsev discloses a device for dissecting the walls of blood vessels. The device utilizes a balloon which presses on a wall of the aorta thereby bending away a scalpel which enters through a window to make incisions in the aorta's central casing.
U.S. Pat. No. 4,445,892 which issued on May 1, 1984 to Hussein et al. discloses a dual balloon catheter device provided with two spaced expandable balloons for occluding a segment of a blood vessel. The patent also provides means for emitting laser irradiation.
International Patent Application No. PCT/US82/01669 of Garrett which published on Jun. 9, 1983 discloses a catheter assembly including a first catheter and a second catheter positionable within the first catheter. An inflatable balloon is fixed to the outer surface of either the first or second catheter. When inflated, the balloon sealingly engages the interior of a body duct. The Garrett patent also discloses the use of a laser beam in order to remove an obstruction in a blood vessel.
U.S. Pat. No. 4,040,413 which issued on Aug. 9, 1977 to Ohshiro discloses one or more inflatable balloons on the outer surface of the tube of an endoscope which encloses a fiber optic light transmitting bundle.